relative humidity
Americannoun
noun
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The ratio of the actual amount of water vapor present in a volume of air at a given temperature to the maximum amount that the air could hold at that temperature, expressed as a percentage. Warm air can hold more water vapor than cool air, so a particular amount of water vapor will yield a lower relative humidity in warm air than it does in cool air.
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Compare absolute humidity
Etymology
Origin of relative humidity
First recorded in 1810–20
Compare meaning
How does relative-humidity compare to similar and commonly confused words? Explore the most common comparisons:
Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
Big Sur’s micro-climate makes firefighting more complicated: The relative humidity drops at night, making fires grow rapidly.
From Los Angeles Times ● Aug. 28, 2026
The heat index is what the temperature feels like to the human body when relative humidity is combined with the air temperature.
From BBC ● Jul. 2, 2026
These included educational attainment, median household income, racial composition, average temperature and relative humidity, smoking prevalence, BMI, and distance to the nearest hospital.
From Science Daily ● Feb. 24, 2026
“The temperature drops and the relative humidity goes up, the winds die down, flames drop to the ground and it starts creeping along,” Hanson said.
From Los Angeles Times ● Dec. 28, 2025
The cloudiness and relative humidity average high on western coasts, with the maximum in the colder season.
From Encyclopaedia Britannica, 11th Edition, Volume 6, Slice 5 "Clervaux" to "Cockade" by Various
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
